Alpha-arylalkanoic acids are widely used as active anti-inflammatory, analgesic, and anti-pyretic pharmaceutical products. Such acids include, for example, ibuprofen, 2-(4-isobutylphenyl)propionic acid and fenoprofen, 2-(3-phenoxyphenyl)propionic acid. Various methods are known in the art for making these acids and their corresponding esters. For example, .alpha.-arylalkanoic esters can be made from corresponding carbonyl compounds of the general formula: ##STR2## wherein at least one of the R.sup.1 and R.sup.2 groups is an alkyl group and the other is a hydrogen atom or an alkyl group or wherein R.sup.1 is a bromine atom and R.sup.2 is an alkyl group (Journal Am. Chem. Soc., 95: 3340 [1973; Synthesis, p. 126 [1981]; Synthesis, p. 456, [1982]; Parkin Transactions (British Chem. Soc.), 1: 235 [1982]; Tetrahedron Letters, 23: 235 [1982], Tetrahedron Letters 22: 4305 [1981]; Journal Organic Chemistry, 43: 2936 [1978]; Chemical Communications, p. 1311 [1982]).
Each of the aforementioned methods has at least one disadvantage, such as requiring the use of a poisonous thallium or lead salt or a precious, and expensive, silver salt, requiring a lengthy reaction time, and producing the desired product in low yields.
Laid-Open Japanese Patent Publication No. 163,345 (1984), incorporated herein by reference, teaches a method of preparing .alpha.-arylalkanoic esters represented by the general formula ##STR3## wherein Ar.sup.1 is an aromatic hydrocarbon group, R and R.sup.1 each represent a hydrogen atom or an alkyl group, and R.sup.2 is an alkyl group, by reacting a compound of trivalent iodine having the general formula ##STR4## wherein Ar is an aromatic hydrocarbon group and X and Y are each a group which can be eliminated as an anion, with a carbonyl compound having the general formula ##STR5## wherein Ar.sup.1, R, and R.sup.1 are as defined above. The reaction takes place in the presence of an orthocarboxylic ester having the general formula ZC(OR.sup.2).sub.3, wherein R.sup.2 is an alkyl group and Z is a hydrogen atom or an alkyl group. Although this method eliminates several disadvantages of methods taught by the prior art, it employs a relatively expensive trivalent iodine compound which may show signs of instability depending upon the groups selected as X and Y. Accordingly, further improvements are sought.
It thus is an object of the present invention to develop an economical method of preparing .alpha.-arylalkanoic ester compounds that is not hindered by the disadvantages of methods known in the art. Other objects of the present invention will become apparent by reading the description of the present invention contained herein.